[FFmpeg-devel] [PATCH] matroskadec, matroskadec, srtenc: Read/Write duration for subtitles. (v2)

Philip Langdale philipl at overt.org
Sun Aug 5 18:17:26 CEST 2012

On Sun, 5 Aug 2012 09:07:25 +0200
Hendrik Leppkes <h.leppkes at gmail.com> wrote:

> On Sun, Aug 5, 2012 at 6:25 AM, Philip Langdale <philipl at overt.org>
> wrote:
> >
> >
> > The original claim was that convergence_duration was needed to avoid
> > overflow on long duration subtitles. This claim seems questionable.
> > If we consider the typical timebase of 1/1000, that still allows
> > for a duration of 8 years. For a 1/1000000 timebase, you still get
> > a 71 minute maximum duration, so I'm not sure where this claim
> > originated from. Only if you go down to a 1ns timebase do you end
> > up with a short max duration of ~4 seconds. Am I missing something?
> >
> >
> There are files with such a timebase. It may not be common, but they
> do exist and they are valid according to the MKV spec.
> So, yes, it is needed for such files, until such a day when the real
> duration is converted to int64 (if ever)

Ugh. This is such a mess. If we really can't move mkv to use duration,
then we've got to go in the other direction.


#define SUBTITLE_DURATION convergence_duration

and use pkg->SUBTITLE_DURATION for now and switch the
define when we can finally break compatibility.


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